Marking apparatus



Aug. 30, 1966 F. H. P. WENDLER MARKING APPARATUS 5 Sheets-Sheet 1 Filed April 27, 1964 ON m? Q? q ON w? Aug. 30, 1966 F. H. P. WENDLER MARKING APPARATUS 5 Sheets-Sheet 2 Filed April 27, 1964 Aug. 30, 1966 H, P wENDLER 3,270,181

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MARKING APPARATUS Filed April 27, 1964 5 Sheets-Sheet 5 United States Patent "ice f 3,270,181 MARKING APPARATUS Friedrich Hermann Paul Wendler, 17 Isher Wood Close, Newton Ayclifie, England Filed Apr. 27, 1964, Scr. No. 362,601 Claims priority, application Great Britain, Apr. 30, 1963, 17,056/ 63 8 Claims. (Cl. 219- 86) The invention relates to means for marking metal and particularly to means for securing identification labels to ingots or slabs of steel while they are still red hot.

In the manufacture of steel, for example, it is important that a slab of steel from a mill should be permanently marked so that it can subsequently be identified, since the use to which it will subsequently be put is governed by the alloy and carbon content of the steel.

Known methods for marking slabs have used a plurality of number and letter stamps, driven by an air blast ram, for impressing on the steel slabs a series of identification markings.

This method of marking the slabs has the disadvantage that as the slab cools, a layer of scale forms on the exterior surface of the slab, and it is sometimes impossible to discover the location of the markings when the block is cold. Also the machine has to be so robustly built to withstand the impact stresses that it is not easily maneuverable into position. Furthermore the changing of the stamps uses up a considerable amountof time, particularly if the stamps have been heated up by contact with the hot slab.

Other methods have used a machine with a two electrode spot welding transformer for welding to the slab an identification label.

This type of machine has the disadvantage that unless the machine is held square to the block, and the surfaces of the block and of the label are both true, then arcing occurs and the label may be burnt up before it can be welded.

Known means for holding the label have included a magnetic block positioned between the electrodes. However, as the block heats up due to its proximity to the hot slab it loses its magnetism. and quickly becomes useless.

The invention has among its objects to provide apparatus for marking metal by securing identification labels to the metal, which is robust but compact, and which minimises the disadvantages of known apparatus.

According to the invention, the apparatus for marking metal comprises a spot welding machine with resiliently mounted electrodes and resiliently mounted holding means for a metal plate or label to be secured to the metal to be marked.

Thus the apparatus may comprise a resiliently mounted plate spot welding machine, including a transformer, at least four resiliently mounted electrodes, cooling means for the electrodes and a plate holding means.

According to the invention furthermore, the transformer may comprise primary and secondary windings, the primary winding being adapted to be connected to a main electric supply, and the secondary winding being adapted to supply four electrodes, two from each endof the windings.

Thus the four electrodes may be mounted so that each is adjacent to one corner of the plate to be spot welded, two electrodes mounted at one side of the plate one above the other, being electrically common, and the two electrodes mounted the other side of the plate, one above the other, also being electrically common.

According to the invention furthermore, the resilient mounting means for the electrodes may comprise a tubular electrode holder mounted so as to slide, against spring pressure, in a box member insulated from the frame of the machine, the electrical loads from the secondary winding of the transformer being secured to the ends of the electrode holders remote from the electrodes, and the electrode holders being non-rotatably mounted.

According to the invention furthermore, means for effecting cooling of the electrodes may be provided and comprise a pressure air feed, hollow electrode holders and perforated electrodes, air being supplied through the end of the machine remote from the electrodes to pass over the transformer windings, through the hollow electrodes and out through perforations provided in the sides of the electrodes, a portion of the air leaving the electrodes being effective to cool the plate holder.

According to the invention furthermore, the plate holder may comprise a rod, connected through a universal joint to a support bracket, spring means being provided to maintain the bracket perpendicular to the rod, and resilient clamps being provided to hold the plate against the support bracket.

According to the invention furthermore, the resilient means for supporting the spot welding machine may comprise a subframe, the subframe comprising a bridge and two spring containing tubes, the body of the machine being adapted to move relative to the subframe by compressing the springs in the tubes.

According to the invention furthermore, the spot welding machine may be suspended from the bridge as by trunnions and position controlled by means of a remotely operable positioning machine.

According to the invention furthermore, the positioning machine may be provided with a support arm for the spot welding machine, the support arm being laterally movable whereby the spot welding machine may be positioned at any required position within the width of a roller track along which roller track the metal to be marked may be conveyed.

According to the invention furthermore, the support arm and the spot welding machine may be movable between an outward or loading position and an inward or working position and between a raised or inoperable position and a lowered or working position.

According to the invention moreover, the lateral movement and positioning may be controlled by an infra red detector adapted to sense the lateral position on a roller track of a hot piece of metal.

The invention is diagrammatically illustrated by way of example in the accompanying drawings in which:

FIGURE 1 is a plan view of a spot welding gun with the top cover removed;

FIGURE 2 is a corresponding elevation of the spot welding gun illustrated in FIGURE 1;

FIGURE 3 is a sectional exploded view of an electrode holder;

FIGURE 4 is a plan view of the plate holder;

FIGURE 5 is an end view of the plate holder;

FIGURE 6 is a sectional view of one of the resilient mounting tubes;

FIGURE 7 is a plan view of a positioning machine and a roller track for conveying hot pieces of metal to be marked, shown with the positioning machine in the inoperative position.

FIGURE 8 is a corresponding elevation of the positioning machine and roller track illustrated in FIGURE 7;

FIGURE 9 is an end view of the positioning machine in the inoperative or loading position; and

FIGURE 10 is a sectional view on the line X-X of FIGURE 9.

Referring to FIGURES 1 and 2, a spot Welding g-un 1 contains a transformer having a primary winding supplied by a cable through a tube 2, advantageously from a 240 AC. supply, and a secondary winding having two loads from each end of the winding, each of the loads being connected to an electrode holder 3. The secondary winding is advantageously adapted to produce 3 volts and a maximum of 9000 amps. Each electrode holder supports and is electrically connected to one of the four electrodes 4. The two electrodes 4, mounted one above the other on the right hand side of the gun, are electrically common and connected in parallel to one end of the secondary winding and the two electrodes 4 connected one above the other on the left hand side of the gun are likewise electrically common and connected to the other end of the secondary winding. Each pair of electrically common electrodes is mounted in a box 5, advantageous- 1y of manganese bronze, and the electrodes are adapted to be independently slidable through holes provided in the ends of the box 5 against the action of springs 6.

As more clearly shown in FIGURE 3 the electrode holder and electrode assembly comprises a bolt 7 adapted to screw into the electrode holder 3 and to clamp the end 8 of the secondary winding securely against the electrode holder. The electrode holder has a forward part 9 adapted to telescope with the part 3 to form a joint, a ring 10 being provided over the joint and the joint being secured by a pin 11. A circlip may be provided in a groove 12 in the part 9.

The electrode 4 is provided for screw threaded engagement with the part 9. The bolt 7, electrode holders 3 and 9, and the electrode 4 are advantageously all provided with a central bore 14. The bore is provided for the passage of compressed air which is supplied to the gun through a pipe 15 (FIGURE 1) and then passes over the transformer windings in the body part 1, through the bolt 7, electrode holders 3 and 4, through the electrode 4 and out through passages 16 provided in the sides of the electrode.

The end of the pins 11 projecting from the rings 10 are adapted to slide in slots in the sides of the boxes 5, to prevent the electrode holders from rotating.

The boxes 5 are insulated from the body 1 by means of insulating layers 17 and are secured in position by insulated clamping strips adapted to be secured by means of screws engaging holes 18 provided in the body of the gun. A holder for the label plates 19, to be welded to the steel slabs, is provided mounted on a shaft 20 positioned between the four electrodes. As shown in FIG- URES 4 and 5 the plate holder comprises a hollow body part 21 of insulating material supporting the spring loaded shaft 20. A screw 22 is provided at the rearward end of the shaft '20 to slide in a slot 23 in the body part 21 to limit the travel of the shaft within the body part.

A spring 24 urges the shaft 20 outwardly from the body part. The body part 21 is secured in the gun by means of a spring loaded downwardly urged locking pin 25 positioned to pass through a hole 26. To prevent cracking of the insulating body part 21 a metal collar 27 may be provided. The shaft 20 is connected through a universal joint 28 to a head part 29, the head part being maintained perpendicular to the shaft 20 by means of a coil spring 30. The head part 29 is provided with a shelf 31, to position the label plates 19, and with clamps 32 to grip the sides of the label. The clamps 32 are adapted to release theplate 19 if the head is pressed against a fiat object by pressing the clamps outwardly against the action of springs 33 mounted on screws 34. The head 29 is prevented from getting hot by the jets of air from the electrode ducts 16.

To prevent damage to the electrodes due to impact with the piece of steel to be marked the spot welding gun is resiliently mounted in a subifraime comprising a bridge 34 and side tubes 35. As shown in FIGURE 6 a web 36 secured to the body part 1 bears at its outer edge a tubular collar 37 adapted to slide on a shaft 38.

Springs 39 and 40 are provided at either side of the collar 37. The shaft 38, and springs 39 and 40 are contained within the slotted tube 35 which has trunnions 41 by which the gun may be pivotally supported. Collar plugs 42 and pins 43 may be used to prevent relative movement between the shaft 38 and tube 35.

The universal joint 28 ensures that the label is pressed firmly against the side of the steel to be marked and the four spring mounted electrodes ensure that at least one electrode of each polarity is pressed firmly against the label plate. A deviation from perpendicular of 15 in either direction of the welding gun from the metal surface to be marked is allowable, without reducing the effectiveness of the weld.

Although not shown in the drawings a micro-switch may be provided at the rear of the shaft 20 whereby movement of the shaft -20 rearwardly into the gun body a determined amount operates the micro-switch to cause electrical power to be supplied to the primary winding of the transformer and to start an electronic timer whereby the gun can be started to weld for a preset time period. Said determined amount, for example, one inch, is set such that when the machine is at an angle of 15 from perpendicular to the slab, the micro-switch is not closed until all four electrodes are pressing the label against the slab.

As shown in FIGURES 7, 8, 9 and 10 the welding gun illustrated in FIGURES l and 6 may be supported adjacent a roller track 44 along which track pieces of metal to be marked, for example ingots 45, may be caused to move by rotation of rollers 46 in the track 4 4, by means of motors 47. The positioning machine for supporting the welding gun may comprise a base 48, adapted to fit around one of the motors 47 and having mounted thereon a cylindrical column 49, the cylindrical colume 49 is rotatable through by means of a rack 50 co-operating with teeth 51 on the column 49. The rack 50 may be driven by a two way pneumatic ram 52. Rigidly secured to the upper end of the column 49 is an arm 53 having mounted thereon a carriage 54. The carriage 54 is supported on the rails 55 and may be driven along the arm 53 by means of an electric motor 550 driving a screw 55b. Supported on the carriage 54 by means of two support arms 56 and a guide arm 57 is a welding gun of the kind described in FIGURES 1 to 6.

As shown in FIGURE 9 the gun is in a raised or inoperative position but it can be moved from this position to a lower or operative position in which position the arms 56 are substantially vertical. The arms 56 are pivoted at 560) and an extension 58 of the arms projects above the upper surface of the carriage 54 and is connected to a rod 59 secured to the piston of a two way pneumatic ram 60. The ram 60 may be supplied with compressed air and the welding gun be supplied with electricity and compressed air by means of flexible conduits suspended in loops from rings 61-on a bar 62 which bar is supported by end struts 63. The positioning machine is thus capable of three movements, that is to say the arm 53 may be over the roller track 44 as shown in solid lines in FIGURES 7 and 8, or it may be he remote from the roller track as shown in FIGURE 9 and in the dot-ted line positions of FIGURES 7 and 8. The carriage 54 may be adjacent the column 49 or at any position along the arm 53 to the outward position shown in FIGURES 7 and 8. The welding gun may be either in the raised or lowered position. In the raised position the welding gun 1s positioned a distance above the roller track greater than the height of the piece of metal which is to be marked, this distance must also be suflicient to allow the gun to clear kerbs 64 provided at the edge of the roller track 44. An infra-red sensing device 65 is provided on the carriage 54 and a further infrared sensing device 66 is provided upstream of the positioning machine at the side of the roller track 44. Advantageously a control cubicle 67 is provided adjacent the outer position of the arm 53 and within the cubicle 67 a stamping machine 6 8, for marking the label plates 19 with the required data, is provided under the control of an operator.

In operation, the sensing device 66 gives an indication to the operator of the presence on the roller track 44 of a red hot piece of metal for example an ingot 45. The operator, having inserted in the plate holder of the welding gun a label plate bearing the relevant data, operates a switch to energise a solenoid valve to cause the ram 52 to move the rack 50 so that the arm 53- is swung out over the roller track 44- to the position shown in FIGURE 7. The carriage 54 then starts scanning towards the column 49 until the detector 65 senses the hot ingot on the track 44, the ingot 45 having been stopped on the track 44 approximately three feet from the positioning machine. The detector 65 automatically centres the carriage 54 so that the welding gun is in line with the end of the ingot 45. The welding gun is then lowered by pressurising the left hand end of the ram 60 as viewed in FIGURE 9, so that the welding gun is substantially parallel to the roller track 44 and about one inch there-above. The motors 47 are then energised to rotate the rollers 46 to feed the ingot 45 so that it crashes into the electrodes 4 of the welding gun. The electrodes and the plate holder are thus forced back into the machine closing the microswitch at the rear end of the shaft 20, starting the electronic timer and connecting the power supply to the primary winding of the transformer. The label plate is thus welded to the ingot and the force of the ingot hitting the welding gun causes the weld-ing gun to recoil thus tripping a switch and energizing the right hand side of the ram 60, as shown in FIGURE 9. This raises the welding gun to the upper position and allows the ingot to pass underneath the gun. The operations after the ingot strikes the gun are practically instantaneous and the gun retracts to the raised position at very high speed.

The arm 53 then swings to the dot-ted line positions shown in F IGURES 7 and 8 under the action of ram 52, the motor 54 turns the screw 55 to move the carriage 54 to the end of the arm 53 remote from the column 49 and the machine is ready for insertion of a further label plate and a further welding operation upon a signal being received from the sensing device 66. In the event of an ingot not reaching the machine after it has been sensed by the detector 66, for example if the ingot is too short and is rejected as scrap, the carriage 54 scans the full Width of the track 44 and contacts a microswitch to return the entire machine to the inoperative position.

As shown in FIGURE 10 the tubes 35 and the bridge 34 of the welding gun may be positioned on top of the gun instead of at the sides of the gun, thus the gun may be positioned closely adjacent the kenbs 64 of the track 44 so that if an ingot travels down the side of the track 44 touching the kerbs 64 it can still be successfully marked.

I claim:

1. In marking apparatus for securing an identification label to a randomly disposed piece of metal, a spot welding machine comprising positive and negative independently resiliently mounted welding electrodes, resiliently mounted holding means for said identification label to be secured to said metal piece, and a transformer connected to said welding electrodes, said spot welding machine being resiliently mounted on a movable support, and remotely operable positioning means being provided for controlling the vertical and transverse position of said spot welding machine, each of said movable support and said positioning means being automatically operable, whereby said label may be welded to said metal piece in any randomly disposed position.

2. Marking apparatus according to claim *1, wherein said transformer is provided with a primary winding and a secondary winding, said primary winding being adapted to be connected to a mains electric supply, and the two ends of said secondary winding being each adapted to supply at least two independently resiliently mounted electrodes,

3. Marking apparatus according to claim 2, wherein said independently resiliently mounted electrodes are provided with tubular electrode holders, said electrode holders being mounted so as to slide against spring pressure in a box member insulated from the frame of said spot welding machine, and wherein electrical leads from said secondary winding of said transformer are secured to the ends of said electrode holders remote from said electrodes, said electrode holders further being non-rotatably mounted.

4. Marking apparatus according to claim 1, in which means for effecting cooling of the electrodes are provided and comprise a pressure air feed, hollow electrode holders and perforated electrodes, the air being supplied through the end of the machine remote from the electrodes and passed over the transformer windings, through the hollow electrodes and out through perforations provided in the sides of the electrodes, a portion of the air leaving the electrodes being effective to cool said identification label holding means.

5. Marking apparatus according to claim 1, in which said identification label holding means comprise a rod connected through a universal joint to a support bracket, spring means maintaining the bracket perpendicular to the rod, and resilient clamps holding the plate against the support bracket.

6. Marking apparatus according to claim 1, in which the spot welding machine is resiliently supported on a subframe, the subframe comprising a bridge, and at least two spring containing tubes, the machine being movable relative to the subframe by compressing the springs in the tubes.

7. Marking apparatus according to claim 1, in which said remotely operable positioning means is provided with a support arm for said spot welding machine and includes first power operated means whereby said support arm and said spot welding machine are movable between an outer position and an inner position, said identification label being loadable into said label holding means at said outer position and spot welded to said metal piece at said inner position; second power 0perated means whereby said spot welding machine is movable relative to said support arm to position said machine at any required position within the width of a roller track, said metal piece being conveyed along said roller track; and third power operated means whereby said spot welding machine is movable between a raised in operable position and a lowered working position.

8. Marking apparatus according to claim 7, including infra-red detector means for sensing the lateral position of a hot piece of metal on said roller track, and electrical means connecting said detector means to said second power operated means, so that when said detector means senses said metal piece said welding machine is moved relative to said support arm to a position in alignment with said metal piece.

References Cited by the Examiner UNITED STATES PATENTS 1,989,266 1/1935 Burns 2l986 2,122,933 7/1938 Eckman 219-86 2,394,822 2/1946 Teplitz 2l986 RICHARD M. WOOD, Primary Examiner. ANTHONY BARTIS, Examiner. 

1. IN MARKING APPARATUS FOR SECURING AN IDENTIFICATION LABEL TO A RANDOMLY DISPOSED PIECE OF METAL, A SPOT WELDING MACHINE COMPRISING POSITIVE AND NEGATIVE INDEPENDENTLY RESILIENTLY MOUNTED WELDING ELECTRODES, RESILIENTLY MOUNTED HOLDING MEANS FOR SAID IDENTIFICATION LABEL TO BE SECURED TO SAID METAL PIECE, AND A TRANSFORMER CONNECTED TO SAID WELDING ELECTRODES, SAID SPOT WELDING MACHINE BEING RESILIENTLY MOUNTED ON A MOVABLE SUPPORT, AND REMOTELY OPERABLE POSITIONING MEANS BEING PROVIDED FOR CONTROLLING THE VERTICAL AND TRANSVERSE POSITION OF SAID SPOT WELDING MACHINE, EACH OF SAID MOVABLE SUPPORT AND SAID POSITIONING MEANS BEING AUTOMATICALLY OPERABLE, WHEREBY SAID LABEL MAY BE WELDED TO SAID METAL PIECE IN ANY RANDOMLY DISPOSED POSITION. 